1. Field of the Invention
The present invention relates to a photosensitive member for electrophotography, and particularly to a photosensitive member for electrophotography which contains a novel hydrazone compound in the photosensitive layer thereof formed on an electroconductive substrate.
2. Description of the Prior Art
Photosensitive materials which have heretofore been used in photosensitive members for electrophotography (hereinafter also referred to as "photosensitive members") include inorganic photoconductive substances such as selenium and selenium alloys, dispersions of inorganic photoconductive substances such as zinc oxide and cadmium sulfide in resin binders, organic polymeric photoconductive substances such as poly-N-vinylcarbazolic and polyvinylanthracene, organic photoconductive substances such as phthalocyanine compounds and bisazo compounds, and dispersions of such organic polymeric photoconductive substances in resin binders.
Photosensitive members are required to have the capabilities of maintaining a surface electric charge in the dark, of generating an electric charge upon receiving light, and of transporting an electric charge upon receiving light. They are classified into two types of photosensitive members, namely the so-called monolayer type photosensitive members, and the so-called laminate type photosensitive members. The former comprises a single layer having all of the above-mentioned functions, and the latter comprises functionally distinguishable laminated layers, one of which contributes mainly to the generation of electric charge, and another of which contributes to the retention of surface electric charge in the dark and electric charge transportation upon receiving light. In an electrophotographic method using a photosensitive member of the kind as mentioned above, for example, the Carlson's system is applied to image formation. The image formation according to this system comprises the steps of subjecting a photosensitive member in the dark to corona discharge to charge the member, illuminating the surface of the charged photosensitive member with imagewise light from a manuscript or copy bearing, e.g., letters and/or pictures to form a latent electrostatic image, developing the formed latent electrostatic image with a toner, and transferring the developed toner image to a support such as a paper sheet to fix the toner image on the support. After the toner image transfer, the photosensitive member is subjected to the steps of removal of the electric charge, removal of the remaining toner (cleaning), neutralization of the residual charge with light (erasion), and so on to be ready for reuse.
Photosensitive members for electrophotography in which use is made of at least one organic material have recently been put into practical use due to the advantageous features of the organic materials such as flexibility, thermal stability, and/or a film forming capacity. They include a photosensitive member comprising poly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-one (disclosed in U.S. Pat. No. 3,484,237), a photosensitive member using an organic pigment as the main component (disclosed in Japanese Patent Laid-Open No. 37,543/1972), and a photosensitive member using as the main component a eutectic complex composed of a dye and a resin (disclosed in Japanese Patent Laid-Open No. 10,785/1972). A number of novel hydrazone compounds have also been put into practical use for photosensitive members.
Although organic materials have a number of advantageous features mentioned above with which inorganic materials are not endowed, however, the fact is that there have been obtained no organic materials fully satisfying all the characteristics required of a material to be used in photosensitive members for electrophotography at the present. Particular problems for known in organic materials have been photosensitivity and characteristics in continuous repeated use.